Surface acoustic wave (SAW) optical modulators are being proposed as an optical engine for three dimensional (3D) display systems. These modulators can provide controllable sub-holograms from which a light field can be constructed.
One type of SAW modulator is the guided-to-leaky-mode device fabricated using lithium niobate as described, for example, in Hinkov et al., Collinear Acoustooptical TM-TE Mode Conversion in Proton Exchanged Ti:LiNbO3 Waveguide Structures, J. Lightwave Tech., vol. 6(6), pp. 900-08 (1988), Smalley et al., Anisotropic leaky-mode modulator for holographic video displays, Nature, vol. 498, pp. 313-317 (2013), herein after “Smalley”; McLaughlin et al., Optimized guided-to-leaky-mode device for graphics processing unit controlled frequency division of color, Appl. Opt., vol. 54(12), pp. 3732-36 (2015), Qaderi et al., Leaky-mode waveguide modulators with high deflection angle for use in holographic video displays, Opt. Expr., vol. 24(18), pp. 20831-41 (2016), hereinafter “Qaderi”; and Savidis et al., Progress in fabrication of waveguide spatial light modulators via femtosecond laser micromachining, Proc. of SPIE Vol. 10115, 2017.
In these SAW modulators, a surface acoustic wave diffracts light propagating in a waveguide and causes at least some of the light to change from a guided mode to a leaky mode that exits the waveguide.